IES VE
Whole-building energy simulation for BREEAM, Part L, and net zero compliance.
What it is
About IES VE
IES VE (Virtual Environment) is the leading whole-building energy simulation platform used in the UK for Building Regulations Part L compliance, BREEAM Ene 01 credits, and net zero carbon design. It builds a 3D thermal model of a building — modelling every room, the construction materials, window sizes and orientations, occupancy patterns, ventilation rates, and HVAC systems — then simulates energy flows hour by hour through a typical meteorological year. The output is an annual energy use intensity (EUI) figure and a breakdown of energy use by end use. Building services engineers and sustainability consultants use IES VE to demonstrate compliance, to compare design options, and to support planning applications where energy or overheating assessments are required. The software's ApacheSim dynamic thermal simulation engine is accepted by UK regulators for SAP and SBEM compliance alternatives, making it the standard tool for complex buildings where simplified compliance tools are not adequate.
What you can do with it
Capabilities
Build a MacroFlo natural ventilation model and assess whether window openings meet CIBSE TM52 overheating criteria.
Run a full NCM (National Calculation Method) analysis and produce a Part L compliance report for a commercial building.
Compare two HVAC strategies side by side and quantify the energy saving from a heat recovery ventilation system.
Model a school building to TM59 criteria for BREEAM Hea 04 thermal comfort credits.
Generate an energy use breakdown by end use (heating, cooling, lighting, DHW) for a net zero feasibility study.
How to learn it
Learning Resources
IES Learning Zone — free training videos and tutorials at learning.iesve.com (requires free account registration)
IES YouTube channel — building energy fundamentals and software walkthroughs
CIBSE TM52, TM54, and TM59 documents — essential reading at cibse.org to understand what the simulation is assessing
University building services engineering programmes include IES VE as standard lab software — student access is free
Pro Tip
Always check your weather file before running any analysis — using the wrong AMY (Actual Meteorological Year) or CIBSE DSY (Design Summer Year) file invalidates overheating results, and regulators do check which file was used.
Skills that use this tool
Roles that use this tool